The History of Ignition Interlock Devices
Ignition interlock devices were one of the most significant advances in vehicle safety in the last century. While they began to spread nationwide in the 90s, their history goes back much farther. There was a long road from the invention to the widespread implementation that we see today.
The story of the ignition interlock truly begins with the introduction of a scientific BAC limit, and the many inventions that were inspired by it.
The Creation of the BAC Limit
The American Medical Association is credited with creating the very first scientific blood alcohol limit. They teamed up with the National Safety Council to perform a range of tests that would determine when someone could be considered impaired. They published the result—.15—in the late 1930s, and it went on to inspire a series of DUI laws across the nation.
.15 is, of course, almost twice the limit that is considered to impair drivers today. You may be surprised to learn that .15 was the standard for nearly 70 years. The standard of .08 BAC used today was not implemented until several months into the year 2000.
Even the higher limit from the 30s inspired a series of inventors to apply their ingenuity to road safety. They went on to create the first breathalyzer devices.
The Creation of Breathalyzer Devices
The first breathalyzer device was invented only a few years after the first DUI laws were put into place. An inventor by the name of Rolla Harger created a device (the Drunkometer) that could create a reading from a breath sample and chemical solution. However, it was a bulky device that could not be easily transported.
The true grandfather of breathalyzer devices is the one that was invented in 1953 by the scientist Robert Borkenstein. Unlike the Drunkometer, it was simple to use. His new mechanism that measured the breath through a combination of chemical oxidation and photometry was far more accurate.
The First Interlock Devices
A little more than a decade after the introduction of the breathalyzer, the first ignition interlock device designed for use in cars was invented. While the vehicles of 1969 are quite different than the ones today, the way that these devices work has not changed.
A sample must be provided by the driver. If the sample is too high, the ignition switch will not fire, and the car will not turn on.
The Spread of Interlock Requirements Across the US
The first ignition interlock devices had some problems, but most of them were solved when the second generation of devices hit the market in the 90s. These devices were far more accurate and ready for a nationwide rollout.
After the perfection of the technology, the spread was rapid. The devices overcame some initial legal challenges to become permitted for use in all 50 states. In half of the states, the devices are not merely permitted, but mandatory for all DUI offenders, even first-time offenders.